Sodium ethoxide → 2-(Bromomethyl)-2,3-dihydro-1-benzofuran

HRID 2296351Notes

Reaction equation

HRID 2296351 reaction equation
[Br-:1].[Br-].[CH2:3]([C:6]1[CH:11]=[CH:10][CH:9]=[CH:8][C:7]=1[OH:12])[CH:4]=[CH2:5].[O-]CC.[Na+]>C(O)C>[O:12]1[C:7]2[CH:8]=[CH:9][CH:10]=[CH:11][C:6]=2[CH2:3][CH:4]1[CH2:5][Br:1]

Participants

4

Reactant 2

HCID 2723922Sodium ethoxideHCID 20472144HCID 20472144, compound

Product 1

HCID 1406372-(Bromomethyl)-2,3-dihydro-1-benzofuranYield 79.7%

Reagents, catalysts & solvents 1

HCID 702EthanolSolvent3×

Procedure

A solution of bromine (90 g) in carbon disulphide (100 ml) was added dropwise to a well stirred solution of O-acetyl-2-allylphenol (100 g) in carbon disulphide (300 ml) at -10° C. over 1 hour. The solution was evaporated to dryness in vacuo, to afford O-acetyl-2-allylphenol dibromide which was immediately dissolved in dry ethanol (300 ml) containing 10 ml of a saturated ethanolic-hydrogen chloride solution. The solution was heated under gentle reflux for 2 hours, and then evaporated to dryness in vacuo. The residue was triturated with n-pentane, and the solid 2-allylphenol dibromide (135 g) was collected and washed twice with portions of n-pentane. The product is pure enough for further reaction. 2-Allylphenol dibromide (135 g) in dry ethanol (300 ml) was treated with a solution of sodium ethoxide (38 g) in ethanol (100 ml) with cooling and stirring, keeping the temperature of the reaction between 30° and 35° C. After addition, the reaction was stirred at room temperature for 1 hour, and then evaporated to dryness in vacuo. The residue was partioned between n-pentane and water. The n-pentane fraction was washed with 2% sodium hydroxide solution, water, and dried (Na2SO4). Evaporation to dryness in vacuo afforded crude (2,3-dihydro-2-benzofuranyl)-methyl bromide (90 g), which distilled at 110°-118° C./0.5 mm to afford product (78 g) of slightly higher purity.

Workup

  1. temperatureThe solution was heated
  2. temperatureunder gentle reflux for 2 hours
  3. customevaporated to dryness in vacuo
  4. customThe residue was triturated with n-pentane
  5. customthe solid 2-allylphenol dibromide (135 g) was collected
  6. washwashed twice with portions of n-pentane
  7. customThe product is pure enough for further reaction
  8. temperaturewith cooling
  9. customthe temperature of the reaction between 30° and 35° C
  10. additionAfter addition
  11. stirringthe reaction was stirred at room temperature for 1 hour
  12. customevaporated to dryness in vacuo
  13. washThe n-pentane fraction was washed with 2% sodium hydroxide solution, water
  14. dry with materialdried (Na2SO4)
  15. customEvaporation to dryness in vacuo
  16. customafforded crude (2,3-dihydro-2-benzofuranyl)-methyl bromide (90 g), which
  17. distillationdistilled at 110°-118° C./0.5 mm

Sources & evidence

ORD record
ord-d7515b2bb1e8493f85df1500b74c7fda
Source dataset
uspto-grants-1984_01
Patent number
US04428940

Reaction notes

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